You could start by eliminating wrong answer(s):
(a) 5 is definitely not a factor of the given 2xy + 8y − 8x − 32,
(d) x^2 - 4x + 16 (not x2 - 4x + 16) is not a factor (it has no y terms)
On the other hand:
(b) 2 definitely divides evenly into 2xy + 8y − 8x − 32: 2(xy + 4y − 4x − 16)
(c) x + 4 divides evenly into both xy + 4y and -(4x + 16):
We get 2(x +4) [y - 4]
